Attention to novel events facilitates adaptation to a changing environment and may increase engagement with one?s surroundings and enhance cognitive abilities. Despite its importance, there has been limited study of age- and disease-related changes in how the brain processes novel events. Based on the PI?s research, a provisional model of a neurally-based novelty processing system is presented. Building upon this work, the proposed research will investigate age-related changes in the novelty P3 response and subsequent allocation of attention to novel stimuli (as measured by viewing durations) in order to elucidate the relationship between responsiveness to novelty and different patterns of cognitive aging. The research aims to distinguish between changes in response to novelty that appear to be inevitable (observed with even the most successful cognitive aging), changes that are most commonly seen with usual cognitive aging, and changes that are associated with the most frequent degenerative disease of the brain (Alzheimer?s disease). A carefully designed series of experiments will test hypotheses about: 1) age-related changes in response to novelty among groups of cognitively high performing individuals; 2) differences in response to novelty between cognitively high and mid performing older individuals; 3) age-related changes in response to novelty among groups of individuals that differ in level of cognitive performance; 4) differences in response to novelty between cognitively normal individuals and cognitively impaired ones (with mild Alzheimer?s disease); and 5) the relationship between the novelty P3 response and subsequent attention to novel events in the laboratory and level of engagement in daily activities. These integrative functional and cognitive neuroscientific studies will extend previous work on the neurology of attention to novel events and provide new insights into the ways in which this fundamental aspect of human behavior is related to normal aging and disease.